The company, Typo Products LLC, said it still plans to launch the product, which attaches to some of Apple Inc's touchscreen iPhone 5 models, at a trade show this week and to begin shipping the keyboards later this month.
"Although we respect Blackberry and its intellectual property, we believe that Blackberry's claims against Typo lack merit and we intend to defend the case vigorously," the company said in a statement on Monday.
"We are excited about our innovative keyboard design, which is the culmination of years of development and research," it said.
Struggling smartphone maker BlackBerry says the Typo keyboard is an attempt to graft its distinctive angled miniature keys on to other smartphones.
© Thomson Reuters 2014
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